Ian Winkelstern Dissertation Defense

Diagenetic and Mineralogical Effects in Clumped Isotope Thermometry and Application to Last Interglacial Climate

Congratulations to Ian Winkelstern who successfully defended his dissertation on March 8, 2016.

Advisor: Kacey Lohmann

Abstract: The relatively new clumped isotope thermometer shows great promise for paleoclimate reconstruction, as it allows for measurement of carbonate formation temperature without assuming water isotopic composition. This dissertation focused on how mineralogical differences affect original clumped isotope (Δ47) values and how they are changed through diagenesis. A primary motivation for this work was to understand the geologic conditions under which the clumped isotope thermometer can be applied with confidence to paleoclimatic problems. Chapter 2 places empirical constraints on on how clumped isotope signatures change during burial, finding alteration in core material 1.3 km below The Bahamas. Chapter 3 is an empirical calibration for dolomite clumped isotope thermometry, enabling future diagenetic and paleoclimatic work. Chapter 4 investigates the partial dolomitization and diagenetic history of a Silurian-aged carbonate complex, and finds clumped isotope signatures altered by diagenetic fluid flow. Finally, the surprisingly cold Last Interglacial temperatures in Bermuda shown in Chapter 5 demonstrate the utility of clumped isotopes for paleoclimate research when applied carefully.